EP1361515A1 - Method and system for database backup - Google Patents

Abstract

The method involves buffering data in a working memory and securing data in background memory for retrieval in the event of a fault, making a first full backup by storing the working memory data contents in a first file in background memory, making a first incremental backup by storing changed or added data since the last incremental backup in blocks in a second file in background memory that grows until storage continues at a program break point. The method involves buffering data in a working memory (M) and securing data in background memory (D) for retrieval in the event of a fault, making a first full backup by storing the data contents of the working memory in a first file (D1) in the background memory, making a first incremental backup by storing changed or added data since the last incremental backup in blocks (1.LOG,..) in a second file (D2) in background memory that grows until storage continues at a program break point. AN Independent claim is also included for the following: (a) system with a database, especially a telecommunications system with a subscriber database.

Description

Name of the invention

The invention relates to a method and a system for Backing up a database with data in one Main memory buffered and on a background memory be backed up so that in the event of an error in the working memory its data content through data retransmission can be produced.

State of the art

A database or database is a program system that Manages all kinds of information centrally. In Many technical systems depend on the fact that Information without delay and without loss of quality must be available.

Switchboards for telecommunication systems manage subscriber-related information in databases, that must be continuously updated and backed up. In Mobile networks monitor so-called Mobile Switching Center, the are switching facilities that connect to the mobile communication participants and to others Switching equipment of a telecommunication network establish the messaging between the mobile Stations. To accomplish this task you are using a or equipped with several subscriber databases, in their RAM the entries are continuously updated. In A so-called home register contains all Data of those participants who have their permanent Location in the coverage area of this Exchange have saved. Furthermore, in this database the information about the current Locations of the mobile stations filed. In one Visitor registers are temporarily the data of those Stations saved that are temporarily in the area stop this exchange. Since the data is only during of a time interval are stored in the working memory this data also as semi-permanent or semi-permanent Data. Because every participant is in the mobile network can move between several radio coverage areas it is required depending on his current location also his participant-specific data in one or in register multiple visitor registries. M.a.W. the Switching equipment of the telecommunication system need both mobility-related as well subscriber-specific data up to date hold. This is done through so-called update procedures, also called a location update, where the changed data for a communication participant in the Database will be noted. So that the data collected at any software or hardware errors in the Switching equipment must not be lost, they must periodically saved on a background memory.

This is a known measure for backing up data Creation of a so-called backup. A backup is one Backup copy of a file or an entire data medium, e.g. a semiconductor RAM. A backup file contains all the information that is required to the original database of a working memory exactly in to restore the state it was in, before the backup was made. At a Real-time database, those information must also be backed up be made during the backup be changed or added. This is done by a Incremental backup. An incremental backup contains the data that compared to the last incremental backup and during the The backup copy was changed or have been added. When restoring the database then not only the last saved backup version of the RAM, but it must also be the last approved and recorded changes in the working memory be loaded back.

The main memory in switching stations is a Semiconductor memory, however, the background memory from A disk storage for cost reasons. The memory access time on the disk storage is compared to that Semiconductor memories are orders of magnitude slower.

Due to the high number of participants and the unhindered Possibility of communication within the cells of a Cellular networks are rising above all in switching centers for Mobile networks meet the requirements for the data throughput rate to secure the database. When in operation Switching computers of a telecommunication network with mobile subscribers can, due to the slow Back up data that entries from participants must be postponed, depending on the duration of the Delay to impairment or even failure of the offered communication service.

Object of the invention

The object of the present invention is a method and to specify a system for backing up a database, the one has high data throughput rate and at the same time is economical.

Presentation of the invention

This object is achieved in a method of type mentioned at the beginning with the characteristic features of Claim 1 and in a system according to characterizing features of claim 8 solved.

Bilden eines ersten Voll-Backups durch Speichern des Dateninhalts des Arbeitsspeichers in eine erste Datei auf dem Hintergrundspeicher;

Bilden eines ersten Zuwachs-Backups, durch Speichern von gegenüber einem letzten Zuwachs-Backup veränderten oder hinzugekommenen Daten des Arbeitsspeichers in Form von Blöcken in eine zweite Datei auf dem Hintergrundspeicher, wobei die Größe dieser zweiten Datei (D2) so lange anwächst, bis das Speichern an einem Programmhaltepunkt anhält.

Die Erfindung sieht also eine Entkoppelung zwischen der Pufferung der Datenänderungen im Arbeitsspeicher und deren Sicherung auf dem Hintergrundspeicher vor. Datenänderungen werden blockweise in einem Zuwachs-Backup auf dem Hintergrundspeicher gesichert.

Indem die Datenbankänderungen in einem zusammenhängenden Stück und nicht direkt an die einzelnen betroffenen Stellen des Backups gespeichert werden, erhöht sich die Datendurchsatzrate bei der Sicherung um das Mehrfache.

Durch die Erfindung ist es möglich, in Betrieb befindliche Vermittlungseinrichtungen für Mobilfunknetze durch einfache Änderungen im Programmablauf an gestiegene Anforderungen anzupassen. Änderungen der Hardware sind nicht erforderlich. Vorhandene Plattenspeicher können beibehalten werden. Es ist nicht erforderlich, das Speichermedium des Hintergrundspeichers durch eine schnelle und kostenaufwendige Speichertechnologie, beispielsweise durch ein RAM-Disk, zu ersetzen.

Es ist von Vorteil, wenn das Programmsystem am Programmhaltepunkt folgende Schritte auslöst:

Bilden eines zweiten Voll-Backups durch Speichern des Dateninhalts des Arbeitsspeichers in eine dritte Datei auf dem Hintergrundspeicher;

Bilden eines zweiten Zuwachs-Backups, durch Speichern von veränderten oder hinzugekommenen Daten des Arbeitsspeichers in Form von Blöcken nach dem Programmhaltepunkt in eine vierte Datei auf dem Hintergrundspeicher.

The method according to the invention is characterized by the following steps:

Forming a first full backup by storing the data content of the working memory in a first file on the background memory;

Forming a first incremental backup, by storing data of the working memory that has been modified or added to that of a last incremental backup in the form of blocks into a second file on the background memory, the size of this second file (D2) increasing until the saving stops at a program stop.

The invention therefore provides for a decoupling between the buffering of the data changes in the main memory and their saving in the background memory. Data changes are saved block by block in an incremental backup on the background memory.

By saving the database changes in a coherent piece and not directly to the individual affected points of the backup, the data throughput rate during the backup increases several times.

The invention makes it possible to adapt switching devices for mobile radio networks which are in operation to simple requirements in the course of the program to meet increased requirements. Hardware changes are not required. Existing disk space can be retained. It is not necessary to replace the storage medium of the background memory with a fast and expensive storage technology, for example with a RAM disk.

It is advantageous if the program system triggers the following steps at the program breakpoint:

Forming a second full backup by storing the data content of the working memory in a third file on the background memory;

Form a second incremental backup by storing changed or added data of the working memory in the form of blocks after the program breakpoint in a fourth file on the background memory.

In this way, two are created on the background memory Full backup and two incremental backup files. By the Forming these files can be done on an adjustable Backup point, an incremental backup is emptied and a full backup be copied. The data content on the Background memory is therefore without time delay and without Loss of quality available for retransmission. The size of the incremental backup is determined by the program breakpoint limited to the background memory. This is ensures that in the event of data retransmission the Loading into the working memory a predetermined loading time does not exceed.

The blocks are advantageously stored sequentially and at equally spaced locations. By adding the buffers strictly in a row and in the order as that Database changes are saved, you get a clear organization on the background memory the growth file.

It is advantageous if information about the size is contained in a file start area.
It is particularly advantageous here if each block in a block start area contains information about the size of the block and a virtual address which assigns the block to a memory location in the full backup. The division of the memory into equal parts facilitates the organization and allocation of the memory areas on the background memory. The virtual address allows a larger address space than is actually available in the working memory.

It is preferred if the working memory is a first Includes buffer and a second buffer and a data block one of these buffers is formed from the data content. By this tandem arrangement of the working memory it is possible that data is read into the working memory at the same time and data stored in the background memory at the same time can be.

When updating the system of a subscriber database it is particularly favorable if the program breakpoint is then is triggered when a predetermined time or Storage threshold is exceeded.

Brief description of the drawings

Figur 1

eine schematische Darstellung eines bekannten Verfahrens zur Sicherung einer Datenbasis;

Figur 2

eine schematische Darstellung des erfindungsgemäßen Verfahrens zur Sicherung einer Datenbasis in einem Vermittlungsrechner;

Figur 3

eine Ausführung der erfindungsgemäßen Datenbanksicherung im Zustand eines Programmhaltepunktes während des Bildens eines zweiten Voll-Backups auf dem Hintergrundspeicher,

Figur 4

eine Ausführung der erfindungsgemäßen Datenbanksicherung im Zustand eines Programmhaltepunktes während des Bildens eines zweiten Zuwachs-Backups auf dem Hintergrundspeicher,

Figur 5

einen Aufbau einer erfindungsgemäßen zweiten Datei,

Figur 6

einen Aufbau eines erfindungsgemäßen Blocks.

Other objects and advantages of the invention can best be understood by reference to the following description in conjunction with the accompanying drawings. The drawings show:

Figure 1

a schematic representation of a known method for backing up a database;

Figure 2

a schematic representation of the method according to the invention for securing a database in a switching computer;

Figure 3

an execution of the database backup according to the invention in the state of a program breakpoint during the formation of a second full backup on the background memory,

Figure 4

an execution of the database backup according to the invention in the state of a program breakpoint while forming a second incremental backup on the background memory,

Figure 5

a structure of a second file according to the invention,

Figure 6

a structure of a block according to the invention.

Implementation of the invention

Figure 1 shows a schematic representation of a conventional method of backing up a database. On such security system is for example at Agencies in a telecommunications system used. A working memory M buffers current data a subscriber database in a memory tandem arrangement, which consists of buffer B1 and buffer B2. The dashed line separates in the schematic Representation of Figure 1, the memory M from Background memory D. File D1 contains a copy of the semi-permanent data of the working memory is therefore a Full backup of the two buffers B1 and B2. A storage program FCTRANS transmits the current subscriber-specific data the buffer to the corresponding storage location of the Background memory. This means that every data entry saved separately in file D1. In the schematic Representation in FIG. 1 is that marked B1 Storage level with several storage cells, 1st location, 2nd location, 3rd location and n. Location marked. The The content of each of these individual memory cells is assigned to one specific location on the background memory saved. This save process is indicated by arrows in the figure 1 indicated. The background memory that is in Exchanges is usually a disk storage has a long time compared to a semiconductor memory Memory access time. A write process takes several Seconds because the read / write head of the magnetic disk storage to a specific point on the magnetic disk position is. There is a backup file very time consuming. Since in the subscriber database each Database change from a mobile communication participant limits the comparatively long access time of the background memory the maximum possible rate of change when logging. At peak utilization of the Communication network can happen that reading from Data from the buffer to the backing store is so slow that the other buffer overflows before the first buffer is completely stored in the background memory. A The consequence of this is that the update of the Participant database is delayed. In a mobile radio system it means that the communication options of the mobile Participant is not only impaired, but it can data may even be lost and Communication options are completely eliminated.

Figure 2 shows a schematic representation of the Method according to the invention for securing a database. Incoming data are, as explained in FIG. 1, in a first buffer B1 and in a second buffer B2 of the Work memory M buffered. To secure this The invention provides semi-permanent data that this Entries not separately, but in blocks in their own File, the second D2, on the background memory D get saved. This is indicated by an arrow in Figure 2 indicated. The second file D2 forms an incremental backup, i.e. a log file with continuously logged changes of RAM. For a reconstruction of the data of the RAM M, it is necessary both the data of the Full backup file D1 as well as that of the incremental backup file D2 to load into memory. Both files together form the content of the last valid and consistent Information content of the working memory. In Figure 2 is the Save process represented by the program FCWRITM. This program summarizes changed or added data of the RAM into blocks, so-called LOGs together and saves them in blocks in the second file D2. Under the Designation LOG is a coherent area of Understand database changes that are in one piece on the Background memory D in an incremental backup, a log or Log file. Saving this contiguous areas lasts for a disk storage only a fraction of a second, making securing one Participant database can be done more efficiently. Every block includes the data content of a buffer B1 or B2. In Figure 2 are the transferred and stored in the second file D2 Blocks identified by 1.LOG, 2.LOG, 3.LOG and last LOG. The file D2 contains these "LOG's" since the last Checkpoint. Because not every entry individually, but each time a full buffer in blocks on the background memory is transmitted, one achieves a decoupling between the Update of the backup file on the background memory and capturing current database entries of the Communication participants in the working memory.

Figure 3 and Figure 4 show a preferred embodiment of the database backup according to the invention in the state after Program breakpoint during the formation of the second full backup D3 and the second incremental backup D4. To each The time in the background memory is always a full and an incremental backup exists. At the program stop the fourth file D4, opened and from that point on Buffer B1 and B2 saved in file D4. At the same time with writing to D4, the third file D3, i.e. the second full backup, with a 1: 1 copy of the working memory formed on the background memory. The memory is in 256 kbyte blocks, between an initial and an end address, in FIG. 3 as "physical BEG" and "physical END ", transferred. The files D1, D2 and D4 form now the last consistent data content of the working memory on the background memory.

Figure 5 shows schematically the structure of the second file D2. An initial area ABD of the file contains information about the file length and the bytes used, in Figure 5 · as "End of LOGFILE" and referred to as "Used Bytes LOGFILE". The individual LOGs are in equidistant storage locations SPST1, SPST2 to SPSTn arranged.

Building a block when creating the first incremental backup D2 and the second incremental backup D4 is schematic shown in Figure 6. In an initial area there are ABB Information about the size and the bytes used, in FIG. 6 referred to as "LOG Size" and as "Used Bytes LOG", contain. The first location and the last location, where each location contains information about "length", contains "virtual address" and "data".

LIST OF REFERENCE NUMBERS

B1

first buffer of the working memory

B2

second buffer of the working memory

D1

first file of the background memory

D2

second file of the background memory

D3

third file of the background memory

D4

fourth file of the background memory

M

random access memory

D

Background memory

Location

memory location

LOG

data blocks

FCWRITE

memory program

SPST

locations

ABD

File initial region

ABB

Block starting area

Claims (8)

Method for backing up a database in which data is buffered in a main memory (M) and backed up in a background memory (D), so that in the event of a fault in the main memory its data content can be restored by data retransmission, characterized by the following steps: Forming a first full backup by storing the data content of the working memory in a first file (D1) on the background memory (D), Forming a first incremental backup, by storing data of the working memory (M) that has been changed or added to a last incremental backup in the form of blocks (1.LOG, 2.LOG, ..., n.LOG) in a second file (D2) in the background memory (D), the size of this second file (D2) increasing until the storage stops at a program breakpoint. A method according to claim 1, characterized in that the following steps are triggered at the program breakpoint: Forming a second full backup by storing the data content of the working memory in a third file (D3) on the background memory (D), Formation of a second incremental backup, by storing changed or added data of the working memory (M) in the form of blocks (1.LOG, 2.LOG, ..., n.LOG) after the program breakpoint in a fourth file (D4) on the background memory (D). Method according to one of the preceding claims, characterized in that the storage of the blocks (1.LOG, 2.LOG, ..., n.LOG) sequentially to equally spaced storage locations (SPST1, SPST2, ..., SPSTn) of the background memory D is done. Method according to one of the preceding claims, characterized in that the second file (D2) and the fourth file (D4) in an initial file area (ABD) each contain information about the respective size of the growth backup. Method according to one of the preceding claims, characterized in that in each block (1.LOG, 2.LOG, ..., n.LOG) in a block start area (ABB) information about the size of the block and a virtual address, which assigns the block to a storage location in the full backup. Method according to one of the preceding claims, characterized in that the working memory comprises a first buffer (B1) and a second buffer (B2) and a data block (LOG) is formed from the data content of one of these buffers (B1, B2). Method according to one of the preceding claims, characterized in that the program breakpoint is generated by exceeding a predetermined time or storage threshold. System with a database, in particular a telecommunications system with a subscriber database, characterized in that the system update of the database or the subscriber database is carried out according to a method according to one of the preceding claims.

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